Tinnitus rehabilitation device and method

ABSTRACT

A tinnitus method and device for providing relief to a person suffering from the disturbing effects of tinnitus is described. The method can be implemented entirely in software to spectrally modify an audio signal in accordance with a predetermined masking algorithm which modifies the intensity of the audio signal at selected frequencies. A predetermined masking algorithm is described which provides intermittent masking of the tinnitus wherein, at a comfortable listening level, during peaks of the audio signal the tinnitus is completely obscured, whereas during troughs the perception of the tinnitus occasionally emerges. In practice it has been found that such intermittent masking provides an immediate sense of relief, control and relaxation for the person, whilst enabling sufficient perception of the tinnitus for habituation and long term treatment to occur. Advantageously the predetermined masking algorithm is specifically tailored to the audiometric configuration of the person. For example, the masking algorithm may be partly tailored to the hearing loss characteristic of the person. A tinnitus rehabilitation device used in conjunction with a personal sound reproducing system is also described.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of U.S. application Ser. No.10/682,894, filed Oct. 14, 2003, which is a Continuation of U.S.application Ser. No. 09/936,687 filed Sep. 17, 2001, now U.S. Pat. No.6,682,472 issued Jan. 27, 2004, which is a National Phase Application ofPCT/AU00/000207, filed Mar. 17, 2000, which designates the U.S. and waspublished in English, and which claims priority to AustralianProvisional Application No. PP 9275 filed Mar. 17, 1999. Each of theseapplications and patents, in their entirety, are incorporated herein byreference.

FIELD OF THE INVENTION

The present invention relates to a tinnitus rehabilitation device andmethod for providing relief and treatment to persons suffering from thedisturbing effects of tinnitus and relates particularly, though notexclusively, to such a method and device that employs intermittentmasking of the tinnitus.

BACKGROUND TO THE INVENTION

Tinnitus is the perception of a sound in the absence of anycorresponding external sound. It is most commonly perceived as aringing, buzzing, whirring type sound, but can also be perceived as abeating, or pounding sensation. Around one third of people who sufferfrom tinnitus can be quite highly disturbed by it. Continuous perceptionof tinnitus can lead to insomnia, an inability to relax, state and traitanxiety, depression, and even suicide in extreme cases. Often closelyassociated with tinnitus is the perception of hyperacusis, which is agreat intolerance to external sounds, even the softer everyday sounds.This distressing condition can even occur as a precursor to tinnitus,and is thought to share the same underlying causes. Thus, everyreference to tinnitus in this document should be construed as includingthe phenomena of hyperacusis or other types of loudness discomfort.

There are very few effective treatment options available for tinnitussufferers, with the vast majority only being advised that “you'll haveto learn to live with it”. Most patients find that they can far morereadily ignore an external sound than their tinnitus. One palliativemethod has been to use hearing aid-style devices that produce a band ofnoise to totally mask the perception of the tinnitus. This gives a senseof relief and control over the tinnitus in around half of patients, butusually has no long-term effect. The prohibitive cost (around A$1500)and aesthetic considerations limits the proportion of sufferers for whomthis is a viable measure. The presence of hearing loss for externalsounds in the tinnitus region often means that the masking noise needsto be unpleasantly loud before the tinnitus can be masked, and the noiseis often judged to be not much better than the tinnitus itself.

In the past four years, a new understanding of the neurophysiologicalprocesses underlying tinnitus has been published, emphasising the roleof the neural pathways in the emergence of distressing tinnitus and thepossibility of using this neural plasticity to retrain its perception.This has been dubbed “Tinnitus Retraining Therapy” or TRT. In thistechnique, patients are given intensive counselling, and use noisegenerators at a volume that does not completely mask the tinnitus. Longterm reductions in tinnitus disturbance have been achieved in somepatients, but it is usual for this process to take at least 18 months oftherapy before any substantial benefit occurs. TRT also offers verylittle immediate sense of relief from the tinnitus, and no relief fromthe associated sleep disturbance and inability to relax.

The closest known prior art to the invention is the “Silentia Set”developed by Starkey Corp., which is a pair of hearing aid devices whichwirelessly receive signals from a stereo system via an induction loopunder a pillow at bedtime. Recording of high frequency noise bands(“water sounds”), babble noise, traffic sounds and music have been usedto mask tinnitus using this system, however the high cost of theSilentia Set make it prohibitive for many sufferers.

Other prior art audiotherapeutic techniques using music are the TomatisMethod developed by Alfred A. Tomatis, and Auditory IntegrationTraining. While neither method is designed for the treatment oftinnitus, the two techniques have some similarities in that they modifymusic for the treatment of auditory disorders. The Tomatis Methodemploys an “Electronic Ear” developed by Alfred Tomatis, (U.S. Pat. No.4,021,611). It has its origins from an extremely outdated model of howthe auditory system works, and has been widely debunked by audiologicalorganisations. Auditory Integration Training is based on the TomatisMethod, but presents the music at extremely loud levels, that may resultin hearing damage, and importation of devices using this technique havebeen banned by the American Food and Drug Administration.

SUMMARY OF THE INVENTION

The present invention was developed with a view to providing a moreeffective rehabilitation technique and device for tinnitus sufferersthat is consistent with contemporary understandings of the underlyingpathology in the auditory system, of which tinnitus is a symptom.

Throughout this specification the term “comprising” is used inclusively,in the sense that there may be other features and/or steps included inthe invention not expressly defined or comprehended in the features orsteps subsequently defined or described. What such other features and/orsteps may include will be apparent from the specification read as awhole.

According to one aspect of the present invention there is provided atinnitus rehabilitation method for providing relief to a personsuffering from the disturbing effects of tinnitus, the methodcomprising:

providing an audio signal spectrally modified in accordance with apredetermined masking algorithm designed to modify the intensity of theaudio signal at selected frequencies whereby, in use, when thespectrally modified audio signal is heard by the person it providessignificant masking of the tinnitus.

Preferably the method further comprises the steps of:

transmitting, using a computer, data representing an audiogram of theperson suffering from tinnitus;

processing said audiogram data at a remote location and producingrequired equalisation response data based on said audiogram data usingsaid predetermined masking algorithm;

receiving, using a computer, said required equalisation response data;and,

combining said required equalisation response data with audio datarepresenting said audio signal to produce said spectrally modified audiosignal.

According to a second aspect of the invention there is provided a methodof using a computer to provide access to a predetermined maskingalgorithm used in tinnitus rehabilitation, for providing relief to aperson suffering from the disturbing effects of tinnitus, the methodcomprising:

receiving on-line, from a user, data representing an audiogram of theperson suffering from tinnitus;

processing said audiogram data using said predetermined maskingalgorithm to produce required equalisation response data based on saidaudiogram data; and,

transmitting said required equalisation response data to the user.

According to a another aspect of the present invention there is provideda tinnitus rehabilitation sound recording for providing relief to aperson suffering from the disturbing effects of tinnitus, the soundrecording comprising:

an audio signal spectrally modified in accordance with a predeterminedmasking algorithm designed to modify the intensity of the audio signalat selected frequencies whereby, in use, when the sound recording isheard by the person it provides significant masking of the tinnitus.

Preferably the predetermined masking algorithm provides intermittentmasking of the tinnitus wherein, at a comfortable listening level,during peaks of the audio signal the tinnitus is substantiallycompletely obscured, whereas during troughs the perception of thetinnitus occasionally emerges. In practice it has been found that suchintermittent masking can provide an immediate sense of relief, controland relaxation for the person, whilst enabling sufficient perception ofthe tinnitus for habituation and long term treatment to occur.

Typically said predetermined masking algorithm is designed to modify theintensity of the audio signal across substantially the full spectralrange of the audio signal. Preferably said audio signal is a highlydynamic signal in which the spectral content and intensity constantlyvaries over time. Most preferably the audio signal is a music signal.However other types of signals including speech or noise might also beemployed.

Advantageously said predetermined masking algorithm is at least partlytailored to the audiometric configuration of the person. Typically saidpredetermined masking algorithm is partly tailored to the hearing losscharacteristic of the person. Preferably the spectral qualities of theaudio signal are modified by the masking algorithm so as to provide arelatively equal sensation level across a major portion of the audiospectrum in both ears. Typically said predetermined masking algorithmalso incorporates a set of calibration figures such as for converting dBHL (Hearing Level) to dB SPL (Sound Pressure Level), or to correct forthe presence of various coupling system types.

According to a still further aspect of the present invention there isprovided a tinnitus rehabilitation device for providing relief to aperson suffering from the disturbing effects of tinnitus the devicecomprising:

signal filtering means adapted to spectrally modify an audio signal inaccordance with a predetermined masking algorithm designed to modify theintensity of the audio signal at selected frequencies whereby, in use,when the spectrally modified audio signal is heard by the person itprovides significant masking of the tinnitus.

Preferably said signal filtering means is a programmable signalfiltering means whereby, in use, the device can be programmed with apredetermined masking algorithm adapted to the particular needs of theindividual suffering from tinnitus.

In a preferred embodiment of the device the predetermined maskingalgorithm is of the form:

REQ=M(SPL+ELC(0.25,0.5,1,2,3,4,6,8,10,12 kHz)−Baseline)

whereREQ=Required equalisation response of the Tinnitus Retraining Protocol

Baseline=0.5 (A−B)+B

A=mean dB SPL at the two adjacent greatest hearing loss frequencies inthe greatest hearing loss earB=mean dB SPL at the two adjacent least hearing loss frequencies in theleast hearing loss earSPL=hearing thresholds (in dB HL) converted to dB SPLELC transfer values for 40 Phon Equal Loudness Contours gainmultiplier=0.3 to 0.95

Preferably M=0.4

However, in an alternative software embodiment of the invention, themathematical algorithm by which the individual prescription of the audiosignal is calculated may differ from the above algorithm. Such otherembodiments of the invention would be consistent with the essentialclinical technique that is intended to provide a modification of theintensity of an audio signal to account for hearing levels specificallyfor the relief and/or treatment of tinnitus and hyperacusis.

Preferably the device is employed in conjunction with a personal musicplayer (PMP) and has an input adapted to connect to the audio outputheadphone jack on the PMP. Preferably the device has a standardheadphone jack to which a standard PMP headphone can be connected.Alternately, a transmitter may be used to transmit a signal to awireless type of receiver that may be placed in the ear canal, conchaarea, behind the ear, or some other area relatively close to the ear.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to facilitate a more detailed understanding of the nature ofthe invention preferred embodiments of the tinnitus rehabilitationdevice and method will now be described in detail, by way of exampleonly, with reference to the accompanying drawing in which:

FIG. 1 is a graphical representation of the long term spectra of both amusic recording and a typical prior art tinnitus masker;

FIG. 2 is a graphical representation of a typical patient's hearingthresholds and their required equalisation curve calculated using afirst embodiment of the masking algorithm;

FIG. 3 is a schematic diagram graphically illustrating intermittenttinnitus masking with music;

FIG. 4 is a graphical representation of the same patient's hearingthresholds and their required equalisation curves calculated using asecond embodiment of the masking algorithm;

FIG. 5 is a schematic block diagram of a possible embodiment of atinnitus rehabilitation device in accordance with the invention; and

FIGS. 6 and 7 are flowcharts illustrating a preferred method ofproviding a tinnitus rehabilitation sound recording in accordance withthe present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Tinnitus masking can be broadly defined as the obscuring of tinnitusperception with an external sound. Hearing aids can provide an effectiveform of environmental noise masking for only around 10% of sufferers.The most reliable audiometric measure of the effectiveness of tinnitusmaskers is the amount of noise required to just mask an individual'stinnitus. This measure is known as the Minimum Masking Level (“MML”).Amongst the most important criteria for successful masking is that theacceptability of a masking stimulus is inversely proportional to itsMML, and that the stimulus needs to be a sufficiently pleasantsubstitute for the tinnitus. In the present inventor's clinicalpractice, several sufferers have reported attempting to use music tofind relief from their tinnitus, but often found that the volumerequired to mask their tinnitus was unacceptably high. Most of thesepersons tended to have a steeply sloping hearing loss characteristic,and a tinnitus pitch which closely corresponded with the edge of themaximal hearing loss frequencies. One of the reasons why previousattempts at using music have not always been successful may be theextremely high co-morbidity of high frequency hearing loss withtinnitus.

Typically, the presence of a sloping high frequency hearing loss wouldmean that at a relaxing sound volume level, only the low pitchcomponents of the music are heard, and therefore the perception of anymusicality and high frequency available for masking is inhibited. Thelong term spectra of both a music recording and a typical prior arttinnitus masker (a Starkey TM5) are illustrated in FIG. 1. A sound levelanalyser was used to average the response of each of the two recordingsover a 64 second period. The spectra were then matched at 1 kHz toenable a comparison of the frequency composition of the two spectra,irrespective of overall sound pressure levels. As can be seen from FIG.1, if the masker is assumed to be the optimal frequency response forhearing impaired listeners, then the unfiltered music has insufficienthigh frequency energy and excessive low frequency response. Therefore,the present inventor has developed a tinnitus masking protocol whichmodifies the frequency response characteristics of an audio signal witha view to overcoming some of the shortcomings of traditional tinnitusmaskers.

Although the following description will be made primarily with referenceto modifying the frequency response characteristics of music, it is tobe understood that a tinnitus masking protocol in accordance with theinvention may also be applied to other types of audio signal suitablefor masking of tinnitus, or for providing auditory stimulation fortinnitus and hypercusis therapy without masking. Furthermore, in view ofthe relatively high cost of traditional hearing aid-style maskers, thefollowing description will give particular emphasis to the use ofconventional, insert or wireless headphone systems or insert typeheadphones in conjunction with a suitable personal sound reproductionsystem such as a high fidelity personal music player (PMP) for audiocassette, CD or MP3 recordings. In Australia, the retail cost of a highfidelity PMP is around one-tenth the cost of conventional binauralmaskers. However, it is to be understood that the tinnitus maskingprotocol according to the invention may also be applicable toconventional hearing aid-style maskers. The technique can also beapplicable to the setting of additional user programs in hearing aids,or the modified signal may be transmitted to the tinnitus suffererthrough their hearing aids' telecoil or induction coil facility.

In addition to the low cost and high portability of PMPs, they generallypossess small headphones with long-throw transducers that enable farsuperior fidelity compared to most free field loudspeaker systems.Furthermore, headphones are generally more effective than loud speakersbecause they circumvent the extensive attenuation of high frequencysounds that occurs through a free field. Changes in PMP earphoneposition on the pinna have been shown to have very limited effects onthe spectral composition of toned sweeps measured in a KEMAR (KnowlesElectronic Mannequin for Acoustic Research).

In developing a tinnitus masking protocol, the required extended upperfrequency stimulus presented challenges for the conversion of audiogramresults to the required real ear response, given that there are as yetno internationally agreed-upon standards for the conversion between dBHL to dB SPL for 10 and 12 kHz pure tone and narrow band noise stimuli.The manufacturer's calibration specifications for a Madsen OB 822audiometer were used to extrapolate the required values for use with atelephonics TDH 39 headphones and MX 41/AR cushions. The audiometer wasprofessionally calibrated accordingly. The values for 10 kHz were 50 dBHL=59.5 dB SPL and at 12 kHz, 50 dB HL=61 dB SPL. All ISO hearing levelfrequencies below 10 kHz were calibrated as per the relevant Australianstandards (AS 1591.2-1987). Table 1 lists the transfer/calibrationvalues in inverted format used for converting dB HL to dB SPL.

TABLE 1 Frequency kHz 0.25 0.5 1 1.5 2 3 3 6 8 10* 12* dB 25.5 11.5 7.06.5 9.0 10.5 10.5 16.5 12.0 9.5 11.0

A further feature of the first tinnitus masking protocol (TMP1)developed by the inventor, was an adaptation of the half gain rule,whereby amplification for hearing loss is most effective when itcompensates for only around one half of the hearing deficit. This ruleunderlies most current hearing aid prescriptive practices. The TMP1attempted to maximise the acoustic energy centred around the pitch ofthe individual's tinnitus, and to “balance” the headphone output tocorrect for any asymmetrical hearing loss. A further goal was to enablethe balanced perception of the masking stimulus throughout the person'shead, rather than at the ear level like traditional uncorrelatedtinnitus maskers.

All PMPs have a volume control range that far exceeds what is availablein hearing aids, and so the TMP1 did not need to specify absolute gainfigures. However, PMPs generally do not possess a left/right balancecontrol, and this was expected to reduce their acceptability in cases ofasymmetrical hearing loss and its associated loudness recruitment. Asthe TMP1 formulae aimed to minimise the perceptual loudness of the musicor noise required to mask an individual's tinnitus, it thus only neededto specify the relative frequency response characteristics for each earwhen presented in those reproduction systems that do not provideindividual control of each stereo channel.

The procedure for applying the TMP1 was thus as follows:

(i) The individual's pure tone hearing level thresholds at eachfrequency were converted to dB SPL by the addition of the transfervalues in Table 1.

(ii) The tinnitus pitch match frequency in the most severely affectedear was chosen for the maximal point of the base line calculation. Thetwo adjacent best hearing thresholds of the lesser hearing loss ear wasalways chosen as the minimum point of the calculation. When a reliablepitch match was not found using pure tones, it was substituted with themean of the two adjacent best hearing frequencies. Thus, the base lineconstituted a mid line value between the two greatest audiometricextremities.

(iii) The final equalisation values were then derived by subtracting thebase line from the hearing threshold (expressed in dB SPL) for eachfrequency and each ear. Thus the algorithm for patients whose tinnituspitch could not be reliably determined was:

Baseline=0.5(A−B)+B

Required Equalisation, REQ=0.5{SPL_((0.25,0.5,1,2,3,4,6,8,10,12 kHz))−Baseline}

The algorithm for non-tonal tinnitus was:

Baseline=0.5(C−B)+B

REQ=0.5{SPL _((0.25,0.5,1,2,3,4,6,8,10,12 kHz))−Baseline}

Wherein,

A=hearing threshold (dB SPL) at frequency of tinnitus pitch match.B=mean dB SPL at the 2 adjacent least hearing loss frequencies.C=mean dB SPL at the 2 adjacent greatest hearing loss frequencies.

Example 1

FIG. 2 is a graphical representation of the relationship between atypical individual's hearing levels, tinnitus and their required TMP1equalisation curves. This individual has a steeply sloping highfrequency bilateral hearing loss and tinnitus at 10,000 Hz, both greateron the left side. Consequently, the required equalisation curves revolvearound the equaliser's baseline, achieving a partial correction forhearing loss by boosting the amount of high frequency gain and alsocorrespondingly attenuating the low frequencies. As the hearing loss andtinnitus is worse on the left, that ear receives correspondingly greateramplification. Because of the abnormal growth of loudness perceptionwhich usually accompanies sensorineural hearing loss, (recruitment,and/or the presence of hyperacusis), complete correction for hearinglevels is not provided, as this may exceed the individual's loudnessdiscomfort levels.

A tinnitus rehabilitation sound recording was then produced on an audiocassette tape for use in the individual's PMP. A stereo frequencyequaliser (Genexxa 31-9082) was used in this procedure, which includesten adjustable frequency bands per channel, with centre frequencies at0.031, 0.062, 0.125, 0.25, 0.5, 1, 2, 4, 8, 16 kHz. Each control had arange of + or −12 dB SPL. The equaliser featured an “EQ record”facility, so that the audio signal could be passed through the equalisercircuit before being recorded. The equaliser's controls for each of theten frequency bands was set to the calculated values for the left ear inthe left channel of the equaliser, and the right ear values set in theright channel, in accordance with the particular individual'sequalisation values as calculated by the TMP1 algorithm. The stereooutput from a broadcast quality cassette recorder was connected to thestereographic equaliser, which then had its output routed to anotherhigh fidelity cassette deck for recording onto high fidelity audiocassette tape. Dual leads and stereo RCA connecters were used topreserve UR channel separation.

Modified sound recordings of both music and white noise were made foruse in clinical trials with 30 participants. Each participant wascounselled as to the rationale behind masking therapy and the possiblebenefits of using the tinnitus rehabilitation sound recording. Eachparticipant was issued with a new PMP with standard insert headphones(Sony MDR E552) that fit into the concha and thus do not require aheadband. Sound level peak analysis measures were then performed. Withtheir custom-made tape playing in the PMP, they were asked to slowlyturn up the volume until they could just no longer perceive their owntinnitus. This level was marked on the volume control wheel. Eachparticipant was told to notify the audiologist if they subsequentlyneeded to turn up the volume further than the marked position. They wereencouraged to experiment downwards with the volume control over thecourse of each masking session, as they might find that they requireprogressively less volume to totally mask if residual inhibitionoccurred.

One group of participants was given a noise tape whereas the other groupwas given a music tape. While both treatment groups has similar levelsof pre-therapy distress associated with their tinnitus, the music groupdisplayed a much greater improvement by mid-therapy and these gains weremaintained at the two-year post-therapy follow up. The noise group alsodisplayed some improvement, but much less dramatic then the music group.96% of the participants found their music or noise tapes to be aneffective masker, which is a far higher acceptance rate than forconventional ear level tinnitus maskers.

In some cases, the TMP1 appeared to present an unbalanced perception ofloudness where the individual possessed a substantial inter-auralasymmetry. The real-ear perception of loudness may have deviated fromthe prescribed response due to perception of loudness differences atvarious points across the frequency range. It was also thought that thehalf gain rule for hearing aids might be best suited for the moderatehearing loss population, and that a mild hearing loss might only requireone-third gain. Furthermore, it is possible that the recruitment ofloudness phenomena might be greater in tinnitus patients thannon-tinnitus patients, particularly given its high co-morbidity withhyperacusis and phonophobia (the fear of external sounds). These factorssuggested that the TMP1 might be over-compensating for hearing loss, andthat further modifications were required to optimise the procedure.

The main purpose of the TMP1 algorithm was to produce an acceptablesubstitute for the tinnitus at the lowest possible MML and toaccommodate for any interaural symmetries. However, it was subsequentlyrealised that an improved masking algorithm would be more robust if theprescription of the required equalisation response was performed solelyon the basis of maximum and minimum hearing levels, and thereby attemptto provide relatively equal sensation levels at all frequencies. Datafrom the TMP1 study indicated that 44.4% of the music group, and 28.6%of the noise group participants preferred to set the volume of theiraudio tapes at a level which only partially masked their tinnitus. Thisoccurred despite being instructed that the optimal setting was tototally mask. The differences in masking level preferences between thetwo types of stimuli also suggests that music was more acceptable thannoise when used at volume levels where the tinnitus could still bepartly perceived. Whilst the historical approach has been to totallymask tinnitus, and the current clinical trend is to partially mask, thepresent inventor has developed an improved tinnitus masking protocolbased on intermittent masking. Since music is a highly dynamic signal,it appears possible that the intensity of music which partially masksmight actually constitute a form of intermittent masking. A schematicrepresentation of intermittent tinnitus masking using a music signal isillustrated in FIG. 3.

Without wishing to be bound by theory, it is believed that theintermittent masking of tinnitus with a relaxing stimulus (such asmusic) may be effective on a psychological, as well as on an acoustic orneural level. In theory, it is feasible that intermittent tinnitusmasking with music might constitute a form of systematicdesensitisation. Whilst in a relaxed state, the listener might bealternatively perceiving, then not perceiving the tinnitus, according tothe fluctuations in the peak levels of the music. The predicability ofthe music may mean that the tinnitus might not even be consciouslyperceived during the “troughs” of the music. Additionally, the tinnitusmight “reappear” from the music often enough for habituation to occur.But the ongoing dynamic nature of the music signal prevents this limitedexposure from being disturbing, and this may reduce any limbic systemenhancement. Thus, the proposedintermittent-masking-with-relaxation-music technique may promote asynergetic effect through its additional mechanisms of facilitating asense of control, a reduction in general anxiety levels, and a form ofauto-hypnosis leading to a reduction of fear about the tinnitus itself.Therefore, an improved masking algorithm based on a tinnitus retrainingprotocol (TRP) was developed that was designed to produce intermittentmasking of the tinnitus.

In practice, the TMP1 algorithm's use of the half-gain rule appeared toover-compensate for hearing loss as noted above, sometimes making therecording seem unbalanced or “tinny”. Conversely, there were severalfactors that suggested that the one-third rule might not providesufficient equalisation. The long term music spectrum has considerablyless high frequency energy than what is typically available fromconventional tinnitus maskers, and yet the greatest hearing loss istypically concentrated in this region (see FIG. 1). Therefore, anysubstantial reduction of gain could prevent achieving adequate highfrequency equalisation to overcome the limitations in the music spectraand the effects of hearing loss. Therefore, because the half gain rulewas sometimes excessive, but one third gain may be insufficient for thepurposes of modifying music for long term tinnitus retraining, a mediumwas selected by the incorporation of a 0.4 gain multiplier, (M).

To further facilitate the provision of equal sensation levels of musicacross the full spectral range of the music signal, the improved TRPalgorithm adopted the ISO Equal Loudness Contours (ELC). The ELCtransfer values correct for any differences in loudness perceptiondepending on the discreet frequencies (International StandardsAssociation, 1961). The 40 phon contour curve was selected because theearlier study found that the mean participant's customised musicrecordings, under total masking conditions, displayed a RMS of 45.7 dBSPL. Thus, with 8 dB representing an approximate doubling of perceivedloudness, 37.7 dB was extrapolated to be the midpoint between thethreshold and total masking, and thus representative of the intensityaround which intermittent masking would occur with those with a mild tomoderate sloping hearing loss. The 40 phon contour was thus utilisedbecause it was the closest to this mid point, and choice of the lowervalue curve also helped compensate for loudness recruitment.

The standard audiometric procedure is to obtain hearing thresholds usingTDH 39 headphones, and the results are expressed in dB HL (HearingLevel). However, the convention for specifying hearing aidcharacteristics is to utilise dB SPL (Sound Pressure Level) values.Consequently the hearing thresholds (dB HL) obtained in the 6 cm³headphones need to be converted into dB SPL by the addition of thetransfer values in Table 1.

These transfer values were then summated with the 40 Phon contourvalues. The resulting transfer/calibration values are displayed in Table2.

TABLE 2 Frequency kHz .25 .5 .75 1 1.5 2 3 4 6 8 10 12 Correc- 23.5 7.55.5 7 6.5 7 5.5 2.5 16.5 21 16.5 13 tions

The tinnitus retraining protocol (TRP) algorithm is a modification ofthe TMP1 algorithm given on page 10 above, and is as follows:

REQ=0.4{ELC+SPL _((0.25,0.5,1,2,3,4,6,8,10,12 kHz))−Baseline}

Where: Baseline=0.5 (A−B)+B

A=mean dB SPL at the two adjacent greatest hearing loss frequencies inthe greatest hearing loss ear.B=Mean dB SPL at the two adjacent least hearing loss frequencies in theleast hearing loss ear.SPL=hearing thresholds (in dB HL), converted to dB SPL.ELC=transfer values for 40 Phon Equal Loudness Contours.

Alternatively, the patient's hearing thresholds may be obtained using ⅓octave narrow band noises, and the gain multiplier (M) becomes 0.7 (orbetween the range of 0.5 to 0.95).

The procedure for applying the TRP was as follows:

(i) The person's audiogram was perused to ascertain the two adjacentgreatest hearing loss frequencies in the greatest hearing loss ear (A),and also the two adjacent least hearing loss frequencies in the leasthearing loss ear (B).

(ii) These four dB HL values were then converted to dB SPL by theaddition of the transfer values in Table 1 (on page 9).

(iii) The dB SPL mean of the two adjacent greatest hearing lossfrequencies in the greatest hearing loss ear (A) was then calculated indB SPL, and the procedure repeated for the two adjacent least hearingloss frequencies in the least hearing loss ear (B).

(iv) A midline value was then calculated by the subtraction of B from A,which value is then halved, and the result added to the B value. This isthe TRP baseline.

(v) All of the dB HL thresholds from the audiogram were then added tothe values in Table 2 above which is the summation of the ISO 40 PhonELC correction values, and the dB HL to dB SPL transfer functions. Thisproduces a measure of hearing in terms of the relative perceivedloudness of stimuli at each of the discrete frequencies. The values wereexpressed in dB SPL so that the desired equalisation frequency responsecould be determined within the 24 dB SPL range of the graphic equaliser.

(vi) The baseline value was then subtracted from each transformedthreshold, and its result then multiplied by the 0.4 gain rule. Thisprocess is repeated for each frequency of each ear.

(vii) These values were then used to manually set the graphic equaliserwith the left ear's required equalisation response (REQ) used in theleft channel, and the right ear's REQ used in the right channel of theequaliser.

Example 2

The audiogram for the participant chosen to demonstrate how the TMP1accounts for a steeply-sloping asymmetrical hearing loss (see Example 1above), was also chosen to demonstrate how the TRP algorithm modifiesthe intensity of the audio signal at selected frequencies to provideintermittent masking of the tinnitus. Tables 3 and 4 below show thecalculations at each frequency for the left and right ears respectivelyusing the TRP algorithm above. The baseline calculation was made asfollows:

Baseline=0.5 (A−B)+B

=[0.5(LSPL ₁₀ +LSPL ₁₂)−0.5(RSPL _(0.5) +RSPL _(0.75]×0.5+0.5)(RSPL_(0.5) +RSPL _(0.75))

=[0.5(89.5+91)−0.5(1.5+8.5)]×0.5+0.5(1.5+8.5)

=(90.25−5)×0.5+5

=47.625

TABLE 3 Corrections and Calculations ELC & SPL transfer L Freq. (Hz) P'sdB HL P's SPL = functions = −Baseline = ×0.4 = REQ 250 5 23.5 28.547.625 −19.15 ×0.4 −7.66 500 −10 7.5 −2.5 47.625 −50.15 ×0.4 −20.06 7502.5 5.5 8 47.625 −39.65 ×0.4 −15.86 1000 15 7 22 47.625 −25.65 ×0.4−10.26 1500 25 6.5 31.5 47.625 −16.15 ×0.4 −6.46 2000 40 7 47 47.625−0.65 ×0.4 −0.26 3000 65 5.5 70.5 47.625 22.85 ×0.4 9.14 4000 60 2.562.5 47.625 14.85 ×0.4 5.94 6000 60 16.5 76.5 47.625 28.85 ×0.4 11.548000 60 21 81 47.625 33.35 ×0.4 13.34 10000 80 89.5 16.5 96.5 47.62548.85 ×0.4 19.54 12000 80 91 13 93 47.625 45.35 ×0.4 18.14

TABLE 4 Corrections and Calculations ELC & SPL transfer R Freq. (Hz) P'sdB HL P's SPL = functions = −Baseline = ×0.4 = REQ 250 20 23.5 43.547.625 −4.15 ×0.4 −1.66 500 −10 1.5 7.5 −2.5 47.625 −50.15 ×0.4 −20.06750 0 8.5 5.5 5.5 47.625 −41.12 ×0.4 −16.85 1000 5 7 12 47.625 −35.65×0.4 −14.26 1500 0 6.5 6.5 47.625 −41.15 ×0.4 −16.46 2000 15 7 22 47.625−25.65 ×0.4 −10.26 3000 45 5.5 50.5 47.625 2.85 ×0.4 1.14 4000 30 2.532.5 47.625 −15.15 ×0.4 −6.06 6000 30 16.5 46.5 47.625 −1.15 ×0.4 −0.468000 20 21 41 47.625 −6.65 ×0.4 −2.66 10000 60 16.5 76.5 47.625 28.85×0.4 11.54 12000 75 13 88 47.625 40.35 ×0.4 16.14

The REQ equalisation curves for both ears are illustrated graphically inFIG. 4. A comparison of FIG. 4 with FIG. 2 will confirm that thepatient's right and left hearing thresholds [HTL (SPL)] curves areidentical.

A second clinical study was conducted in which 90 people who suffer fromtinnitus participated. The participants were allocated with blockrandomisation into one of four treatment groups: one group to test asecond generation total masking algorithm (TMP2), one to test thetinnitus retraining algorithm (TRP), one to empirically measure thecurrent TRT approach of using low-level broadband noise stimulants, anda quasi-control group to receive counselling alone. The second studyexceeded expectations, with dramatic levels of habituation experiencedby more than three-quarters of the participants using spectrallymodified music. The adoption of bibliotherapy and TRT-style counsellingresulted in significant improvements in clinical outcomes for alltreatment groups. However, counselling alone appeared to be insufficienttreatment for most participants. An important finding was that the TRPgroup experienced the greatest mean improvements in tinnitus distress.The TMP2 stimulus group initially displayed a more rapid improvement,but the more gradual gains of the TRP group were sustained for longer,and ultimately were superior. There was little difference between thenoise and counselling alone groups at post therapy and follow-up,although the mean improvements experienced by the counselling alonegroup were ultimately not statistically significant. While all treatmentgroups recorded mean reductions in tinnitus distress over therapy, thetwo music groups ultimately appeared to be the most effective.Approximately three-quarters of the two music group participantsexperienced significant habituation to their tinnitus (TMP2=78.6%,TRP=75%)_(.)

There were substantial reductions in hyperacusis scores for both musicgroups, and a slight reduction for the noise group. The group withoutacoustic stimulation (Counselling-only) displayed an increase inhyperacusis over the same period, strongly indicating that the provisionof acoustic stimulation was a key ingredient in the hyperacusisimprovements. The music group participants often reported that theirhyperacusis levels tended to improve faster than their tinnitusperception.

The clinical studies therefore suggest that total masking with music ismore effective to facilitate a rapid improvement in distress andrelaxation levels, despite the fact that intermittent masking with musiceventually proved to be more effective on several measures. Thisindicates that a two-stage approach might be most efficient, wherebypatients initially should employ a total masking algorithm to give astronger sense of relief and control, then later switch to intermittentmasking to remove the tinnitus detection.

In the clinical studies, pre-recorded music was spectrally modifiedusing the predetermined masking algorithms, and re-recorded on audiocassette tapes for participants' use. This approach is unlikely to beacceptable for widespread clinical use, in view of the potentialcopyright infringement problems in some states or countries. Purchase ofthe rights to re-record music from selected recording companies is onemeans of circumventing this, or the commissioning of recordingsspecifically for this purpose. In one embodiment it is proposed toprovide a programmable “black box” device for use by privatepractitioners. The device thus envisaged can be programmed by aqualified audiologist to account for each individual's tinnitus andhearing loss characteristics, using the tinnitus masking algorithms andclinical protocols developed by the inventor. In one embodiment, thedevice may take the form of a musician's hearing aid-type devicedesigned to spectrally modify the audio signal as it enters the wearer'sears. A more preferred embodiment is to provide the device in the formof a “black box” which can be employed in conjunction with a PMP and hasan input adapted to connect to the audio output headphone jack on thePMP. The device would have a standard headphone jack to which aconventional PMP headphone can be connected. In an alternativeembodiment, a modified sound recording is automatically generated in theaudiologist's clinic, tailored to the patient's audiometricconfiguration, using software accessed via the World Wide Web.

FIG. 5 illustrates in schematic block diagram form a possible embodimentof a tinnitus rehabilitation “black box” device. The device 10 has aninput 12 adapted to receive a two-channel stereo signal from theheadphone output jack of a PMP. The device 10 also has an output 14which provides a two-channel stereo signal, spectrally modified by apredetermined masking algorithm programmed into the device 10, which issuitable for listening to through a conventional PMP headphone.Preferably, the device 10 employs digital signal processing, andtherefore the left and right input audio analog signal is converted todigital format in an analog to digital converter (ADC) 16. The digitaloutput signal of ADC 16 is then sent to a digital filter 18 whichfilters the digitised audio signal in accordance with a predeterminedmasking algorithm. The digital filter 18 modifies the intensity of theaudio signal at selected frequencies in accordance with the maskingalgorithm.

The filter characteristic of the digital filter 18 may be programmedmanually using thumbwheels. However, more preferably the digital filter18 is programmed electronically by means of a microprocessor-basedcontroller 20 having a communications port 22 that may be connected to adesk top computer. Using a custom-designed software program whichaccompanies the device 10, an audiologist or other hearing aid dispensercan program the device 10 by means of a graphic user interface (GUI)which facilitates the input of the required clinical data into thenon-volatile memory of the controller 20. Thus, for example, theclinical audiologist would simply enter the patient's pure tone hearinglevel thresholds at each of the 10 discrete frequencies from 0.25 to 12kHz. The audiologist may also be required to enter the two adjacentleast hearing loss frequencies (B) the hearing threshold at thefrequency of tinnitus pitch match (A) and/or the two adjacent greatesthearing loss frequencies (C). Either the software or the controller 20will then use these figures to calculate the baseline value, and employthe predetermined masking algorithm to calculate the requiredequalisation values. These values are employed by the controller 20 toset the filter constants at each frequency in the digital filter 18.

The device 10 may also include an additional signal processing means 24,which is also under control of the controller 20, for providing furtherspectral modification of the digital audio signal after filtering by thedigital filter 18. The spectrally modified audio signal is thenconverted back to analog format in a digital to analog converter (DAC)26. An amplifier 28 may be provided to control the amplitude of theanalog output signal provided at the output 14 of the device. It will beunderstood that each of the digital components of the device 10 may beintegrated into a single integrated circuit, so that the dimensions ofthe device 10 can be made quite small and the device therefore remainsinconspicuous.

Further investigation has revealed that the proprietary algorithms ordigital processing of the audio signal may be entirely software-based,facilitating the production of a stored music medium (compact disc oralternative format) for playback by the tinnitus sufferer on a standardpersonal sound reproduction system, such as a personal music player(PMP), with headphones. In this embodiment, the method of providing atinnitus rehabilitation sound recording takes full advantage of thespeed and economies provided by the Internet for fast digitalcommunications and remote processing power. With no more than a desktoppersonal computer (PC) with CD-writing capability, the ability toprovide a customised tinnitus rehabilitation sound recording can beplaced at the fingertips of the audiologist. By utilising the reach ofthe World Wide Web and developing an application service provider (ASP),(also described as “on-line operating software”), the method can beextended to provide tinnitus relief and treatment to a global market.FIGS. 6 and 7 illustrate in flowchart form a preferred method ofproviding a tinnitus rehabilitation sound recording utilising the WorldWide Web and the services of an ASP.

The process commences in the audiologist's clinic where the patientconsults 100 with the audiologist. The audiologist enters 102 thepatient's personal details into the appropriate fields in an applicationform located on a proprietary website. The audiologist then conducts 104an audiogram on the patient's left and right ears. The audiogram isconverted into an appropriate digital format and stored 106 on theaudiologist's PC. The audiologist may then activate 108 the applicationservice provider (ASP) via the website, which automatically accesses thepatient data, including the digital audiogram, and transmits it via thewebsite to the ASP.

Data is received 200 by the ASP and split into left and right earprocessing channels. A central processing server (accessed via the ASP)houses the software containing the proprietary algorithms for convertingthe patient data to a digital filtering format herein referred to as aMasking Profile. This Masking Profile is then transmitted back to theaudiologist's PC. The central processing server uses the digitalaudiogram to determine 202 _(L), 202 _(R) the pure tone level thresholdsat each of the predetermined frequencies for the left and right ears.The software ascertains 204 the two adjacent greatest hearing lossfrequencies in the greatest hearing loss ear, and also the two adjacentleast hearing loss frequencies in the least hearing loss ear. In each ofsteps 206 _(L), 208 _(L), 210 _(L), 212 _(L), 214 _(L), 216 _(L) and 206_(R), 208 _(R), 210 _(R), 212 _(R), 214 _(R), 216 _(R) the tinnitusretraining protocol algorithm is applied to the left ear and right earlevels respectively, as is illustrated graphically in Tables 3 and 4above.

In steps 218, 220 and 222 the baseline value is calculated, which issubtracted from each of the transformed threshold values for the leftand right ears at 210 _(L), 210 _(R). The left and right ear RequiredEqualisation Response (REQ) values are then transmitted 224 to theaudiologist's PC via the ASP website. The website, which is visible onthe audiologist's PC, notifies 226 the audiologist that the REQ valuesare being downloaded onto the audiologist's PC, and also prompts 302 theaudiologist to insert a music CD into a CD player connected to the PC.The audiologist is also prompted 304 to insert a blank CD into the CDwriter connected to his PC. It is to be understood that any suitableaudio recording may be employed, preferably a music recording, stored onany suitable storage medium, such as a compact disc, audio cassette orMP3 card. Typically, the patient is offered a choice of music CD's, forwhich the appropriate copyright licence fees have been paid, to be usedas the base recording. An audio software application on theaudiologist's PC accesses 306 the CD recording 308 and stores 310 theaudio data to a file in the memory of the PC.

Proprietary software accessed by the ASP online reads the audio filesstored in the PC, splits the signal into left and right stereo signalsand converts them to Fast Fourier Transform 312 (FFT) format 314.Meanwhile, the REQ data received by the audiologist's PC is allocated316 a channel reference (ie left channel data and right channel data318). The software then converts 320 this left and right channel datainto left and right Masking Profiles 322 respectively. Software providedon the audiologist's PC accesses 324 and applies the Masking Profiles tothe right and left FFT signals for each of the stored songs in order toproduce the left and right channels of the spectrally modified musicsignal. Proprietary software 326 converts 326 the modified left andright signals back to the frequency domain for playback as aconventional audio file. The modified audio files 328, one correspondingto each of the songs on the original music CD, are then utilised 330 bythe CD Writer Software stored in the audiologist's PC, and are writtento a blank CD 332.

The advantage of using an ASP and the audiologist's PC is that theamount of data transmitted and the processing power required by theserver is in relative terms, very low. It is the processing of the audiosignal that requires the bulk of the processing power. Via this modelthat power is housed in the PC of the audiologist instead of the server.Processing time would be negligible and therefore the entire processcould be encompassed in the one patient visit.

Transmission is either via e-mail using a secure line with encryption orvia a password-restricted web page; only qualified audiologists havingaccess. Additional security measures such as ‘one-time-only-downloads’or limiting the time the data is available on the website are alsopossible.

The consultation can easily be held in conjunction with a therapysession with the audiologist, or as part of a coordinated therapy regimeof on-going treatment. Possible revenue streams include the download ofthe proprietary software from the website and a royalty on each datadownload, ie. for each CD made (not per patient, as each patient maywish to modify more than one CD). The Internet website could alsoprovide a number of other services to assist in the relief of andtreatment of tinnitus and hyperacusis. Thus, while music is thepreferred embodiment, CDs can also be produced using noise,environmental sounds, pure tones, or even speech signals if this isstrongly preferred by the sufferer. The more computer-literate suffererscould enter their audiogram details without the help of an audiologist.When the audiologist or hearing aid dispenser does not have a CD burner,facility will be available for the CD to be produced at the ASP or othersite, then posted to the clinic. As the data transmission speed of theInternet significantly increases, facility will be available for theprocessing of the audio signal to be performed within the ASP server ifrequired.

Now that several embodiments of the tinnitus rehabilitation method anddevice have been described in detail, it will be apparent that thedescribed method and device for providing relief for persons sufferingfrom tinnitus has a number of significant advantages over prior arttechniques, including the following:

(i) by facilitating the use of a personal music player with relaxingmusic, it is much more acceptable to patients than conventional hearingaid-style maskers;

(ii) it compensates for high frequency hearing loss which accompaniesthe tinnitus in approximately 80% of cases, thus providing the broadestspectrum of acoustic stimulation;

(iii) the masking algorithms developed to spectrally modify themasking/retraining audio stimuli correct for each individual'sparticular hearing loss configuration as well as accounting for theeffects of loudness recruitment, thus enabling effective stimulation ata relaxing intensity level;

(iv) intermittent tinnitus masking with music can provide a form ofsystematic desensitisation to the disturbing effects of tinnitus; and,

(v) spectrally modified sound recordings produced using the maskingalgorithms reduce tinnitus distress to the point where it was no longersignificantly interfering with quality of life in more than 75% of trialparticipants. Significant reductions in MMLs were measured, andhyperacusis levels had significantly improved.

It will also be apparent to persons skilled in the audiological andelectronics arts that numerous variations and modifications may be madeto the described method and device, in addition to those alreadydescribed, without departing from the basic inventive concepts. Forexample, a masking algorithm in accordance with the invention may beemployed to set the frequency response of existing tinnitus maskerswhich use bands of noise, rather than music, to achieve similar results.Various types of noise, pure tones and speech could also be used inaddition to music. The same masking algorithms may also be employed inexisting wireless receiver devices, (such as the Starkey Silentia Set),or through hearing aid induction coil systems. Furthermore, themathematical algorithms used for calculating the individual prescriptionof the audio signal may differ from the above-described algorithms, andextra sounds may also need to be inserted. However, other embodiments ofthe invention would be consistent with the essential clinical techniquethat is intended to provide a modification of the intensity of audiosignals to account for hearing levels, specifically for the reliefand/or treatment of tinnitus and/hyperacusis. All such variations andmodifications are to be considered within the scope of the presentinvention, the nature of which is to be determined from the foregoingdescription and the appended claims.

1. A method of providing treatment for an auditory system disordercomprising: generating a treatment signal by accentuating frequencycomponents in a signal in a frequency range where a person has deficienthearing and ameliorating any objectionable nature in the treatmentsignal by including coherent signal components within a generallistening range of the person.
 2. The method of providing treatment foran auditory system disorder as claimed in claim 1, wherein anyobjectionable nature in the treatment signal is further ameliorated byattenuating the signal in frequencies where a person's hearing isrelatively less deficient.
 3. The method of providing treatment for anauditory system disorder as claimed in claim 1, wherein the auditorysystem disorder is tinnitus and the treatment signal is a maskingsignal.
 4. The method of providing treatment for an auditory systemdisorder as claimed in claim 3, wherein the treatment signal includes afrequency substantially similar to the tinnitus.
 5. The method ofproviding treatment for an auditory system disorder as claimed in claim1, wherein the treatment signal is a highly dynamic signal whosespectral content and intensity constantly varies over time.
 6. Themethod of providing treatment for an auditory system disorder as claimedin claim 5, wherein the treatment signal is a music signal.
 7. Acomputer readable recording medium on which is recorded a program forcarrying out the auditory system disorder treatment method as defined inclaim
 1. 8. A carrier signal encoded to transmit, via a global computernetwork, a computer executable program for carrying out the auditorysystem disorder treatment method as defined in claim
 1. 9. A method ofproviding treatment for an auditory system disorder of a patientcomprising: exposing the patient to a treatment signal; and manipulatingapplication of the treatment signal to the patient so that the patient'sperception of the auditory system disorder is modified on a neural levelwherein the patient is gradually desensitized to the auditory systemdisorder over time, to thereby habituate the patient to the auditorysystem disorder.
 10. The method of providing treatment for an auditorysystem disorder of a patient as claimed in claim 9, wherein thetreatment signal is specifically tailored to the patient.
 11. The methodof providing treatment for an auditory system disorder of a patient asclaimed in claim 9, wherein treatment signal includes components thatare specifically tailored to each ear of the patient.
 12. The method ofproviding treatment for an auditory system disorder of a patient asclaimed in claim 11 wherein treatment signals are delivered in abinaurally balanced way.
 13. The method of providing treatment for anauditory system disorder of a patient as claimed in claim 9, wherein thetreatment signal is a highly dynamic signal whose spectral content andintensity constantly varies over time.
 14. The method of providingtreatment for an auditory system disorder of a patient as claimed inclaim 13, wherein the treatment signal is a music signal.
 15. The methodof providing treatment for an auditory system disorder of a patient asclaimed in claim 9, wherein the treatment signal includes at least anactive treatment portion which is spectrally modified to patientspecifications.
 16. The method of providing treatment for an auditorysystem disorder of a patient as claimed in claim 9, wherein thetreatment signal includes at least one passive treatment portion suchthat delivery of the active treatment portion is more comfortable to andpossibly not perceived by the patient, whereby the patient becomeshabituated to the auditory system disorder by gradually increasing theexposure to the auditory system disorder during treatment.
 17. Themethod of providing treatment for an auditory system disorder of apatient as claimed in claim 9, wherein the auditory system disorder istinnitus and the treatment signal is a masking signal.
 18. The method ofproviding treatment for an auditory system disorder of a patient asclaimed in claim 9, wherein the treatment signal is a music signal. 19.The method of providing treatment for an auditory system disorder of apatient as claimed in claim 9, wherein the treatment signal accounts fora person suffering from a condition characterized by reduced toleranceto sound.
 20. The method of providing treatment for an auditory systemdisorder of a patient as claimed in claim 19, wherein the conditionincludes hyperacusis.
 21. The method of providing treatment for anauditory system disorder of a patient as claimed in claim 9, wherein thetreatment signal is applied intermittently to the patient to provideactive treatment periods in which the auditory system disorder isactively treated and passive treatment periods in which the auditorysystem disorder may exist but not necessarily be perceived by thepatient.
 22. The method of providing treatment for an auditory systemdisorder of a patient as claimed in claim 9, further comprisingproviding the treatment signal via an external device.
 23. The method ofproviding treatment for an auditory system disorder of a patient asclaimed in claim 22, wherein the external device comprises headphones,earphones or wireless earphones.
 24. The method of providing treatmentfor an auditory system disorder of a patient as claimed in claim 9,further comprising providing the treatment signal via an internaldevice.
 25. The method of providing treatment for an auditory systemdisorder of a patient as claimed in claim 9, further comprisingproviding the treatment signal via a hearing insert.
 26. A method forproviding treatment for a patient's auditory system disorder,comprising: measuring the patient's hearing loss characteristics;calculating an optimal gain for each hearing threshold at each frequencyin each ear; and applying the contour curve to a dynamic input signal toobtain an individually prescribed ideal output signal.
 27. The methodfor providing treatment for a patient's auditory system disorder asclaimed in claim 26, wherein at least a main portion of the outputsignal is centered near a mid point of two extremes of the patient'shearing configuration.
 28. The method for providing treatment for apatient's auditory system disorder as claimed in claim 26, wherein therelevant transform values for dBHL to dBSPL, optimal gain multiplierfunctions, or frequency-dependant loudness weighting curves are takeninto account to provide a balanced perception of the signal in each ear.29. The method for providing treatment for a patient's auditory systemdisorder as claimed in claim 26, wherein the auditory system disorder istinnitus and the output signal is generated by spectrally modifying anaudio signal as it enters the wearer's ears.
 30. The method forproviding treatment for a patient's auditory system disorder as claimedin claim 26, wherein the auditory system disorder is tinnitus and theoutput signal is a masking signal.
 31. The method for providingtreatment for a patient's auditory system disorder as claimed in claim26, wherein the treatment signal is a highly dynamic signal whosespectral content and intensity constantly varies over time.
 32. Themethod for providing treatment for a patient's auditory system disorderas claimed in claim 31, wherein the treatment signal is a music signal.33. The method for providing treatment for a patient's auditory systemdisorder as claimed in claim 26, wherein the centering is bi-lateralcentering and is performed by determining the greatest hearing ear ofthe patient and noting the hearing thresholds at a greatest hearing lossfrequency region; determining the least hearing loss ear and noting thehearing thresholds at the least hearing loss frequencies; andcalculating a midpoint between the two extremes to define a baselinefrom which approximately equal amounts of acoustic energy can be addedor subtracted, thus maximizing usable range while minimizing distortion.34. The method for providing treatment for a patient's auditory systemdisorder as claimed in claim 26, wherein the centering is performed bydetermining the midpoint between the desired ear's worst hearingthreshold region and the same ear's best hearing threshold region, todefine a baseline value from which approximately equal amounts ofacoustic energy can be added or subtracted, thus maximizing usable rangewhile minimizing distortion.
 35. The method for providing treatment fora patient's auditory system disorder as claimed in claim 26, wherein theperception of the signal in each ear is maintained by a correlation intime between two different signals.
 36. A method of treating tinnituscomprising generating a treatment signal by accentuating frequencycomponents in a signal in a frequency range where a person has deficienthearing and which treatment signal includes a frequency substantiallysimilar to the tinnitus.
 37. A method for treating tinnitus as definedin claim 36, further comprising ameliorating any objectionable nature inthe masking signal by including coherent signal components within ageneral listening range of the person.
 38. A method for treatingtinnitus as defined in claim 37, wherein the treatment signal is a musicsignal.
 39. A computer readable recording medium on which is recorded aprogram for carrying out the tinnitus treatment method as defined inclaim
 37. 40. A carrier signal encoded to transmit, via a globalcomputer network, a computer executable program for carrying out thetinnitus treatment method as defined in claim
 37. 41. The method ofproviding treatment for an auditory system disorder of a patient asclaimed in claim 1, wherein the treatment signal accounts for a personsuffering from a condition characterized by reduced tolerance to sound.42. The method of providing treatment for an auditory system disorder ofa patient as claimed in claim 41, wherein the condition includeshyperacusis.
 43. The method of providing treatment for an auditorysystem disorder as claimed in claim 37, wherein the treatment signal isa highly dynamic signal whose spectral content and intensity constantlyvaries over time.